Television tuning system with means to prevent loss of information during power outages

ABSTRACT

A television tuning system with a circuit for preventing the loss of information during power outages is disclosed. A disable signal is generated in response to the interruption of a mains power supply. In response to the disable signal, a series of fixed signals are applied to at least one of the date and address terminals of a memory containing the information to be preserved. An appropriate signal for preventing the information stored in the memory from being changed during the period in which the disable signal is generated is also applied to the memory.

RELATED APPLICATION

This is a divisional of U.S. patent application Ser. No. 040,079, filed May 17, 1979 now U.S. Pat. No. 4,314,375, issued Feb. 2, 1982.

BACKGROUND OF THE INVENTION

The present invention is directed towards a television tuning system which includes a circuit for preventing the loss of information stored in a memory and used by the television tuning system during its operation during power outages.

Electronic tuning systems are well known in the art. Such systems normally include a memory which stores information concerning the operating parameters of the television such as the frequency of channels which are to be tuned to, desired volume, brightness and color settings, etc. The memory also often stores other information such as the time of day, etc.

It is important to preserve the foregoing information in the case of power outages. This can be done using a permanent external memory (a battery-supplied, low consumption CMOS memory or non-volatile MNOS memory). Nevertheless, it has been shown that part of the data in the memory may be lost during the transient state between the loss of power and the return of the power.

It is a primary object of the present invention to provide a circuit arrangement designed to prevent loss of part of the data in the memory during the transient state between the loss of power and the return of the power.

SUMMARY OF THE INVENTION

In order to achieve the foregoing and other objects of the invention which will be clear from the following description thereof, the present invention is directed towards an apparatus for use with a television receiver, the apparatus comprising:

a power circuit for converting a mains power supply voltage to a reduced voltage which is applied as a power signal to several components of said television receiver, said power circuit generating said reduced voltage shortly after said mains power supply voltage is applied thereto and maintaining said reduced voltage until shortly after said mains power supply voltage is removed therefrom;

a read/write memory for storing information relating to the operating parameters of said television receiver, said memory having data terminals, address terminals, and one or more control terminals for controlling operation of said memory;

a control circuit for controlling said operating parameters of said television receiver as a function of said information stored in said memory and as a function of data signals applied thereto, said control circuit changing the values of said information stored in said memory by applying control signals to said data and address terminals of said memory in response to specific data signal applied to said control circuit;

first means for generating a disable signal responsive to an interruption of said mains power supply voltage, said disable signal being generated before said reduced voltage is cut off in response to the removal of said mains power supply voltage from said power circuit, said disable signal continuing until after said reduced voltage is again generated by said power circuit in response to the reapplication of said mains power supply voltage to said power circuit;

second means responsive to said disable signal for supplying a series of fixed signals to at least one of said data and address terminals of said memory; and

third means responsive to said disable signal for applying to at least one of said control terminals of said memory an appropriate signal for preventing said information stored in said memory from being changed during the period in which said disable signal is generated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows the block diagram of part of a television receiver according to the present invention;

FIGS. 2, 3 and 4 show block diagrams of elementary logic functions performed by the circuits on the device according to the present invention;

FIGS. 5 and 6 show a number of FIG. 1 circuits in greater detail;

FIG. 7 shows the block diagram of a perfected version of the circuit of FIG. 1--only the differing features are shown.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Number 1 in FIG. 1 indicates a receiving aerial connected to varicap-diode tuner 2 which generates a signal converted to intermediate frequency IF at its output. The tuner is the known type and consists essentially of a selective amplifier stage, a mixer circuit and local oscillator circuit.

One output on the local oscillator circuit is connected to a first frequency-divider circuit 3 which divides by a fixed number N1 and whose output is connected to the signal input of a second divider 4 which divides by a variable number N determined by 12-bit signal, which means it can divide by any number from 1 to 2¹².

The output of divider 4 is connected to a first input of phase-frequency comparator circuit 5 to whose second input a reference signal generated by quartz generator 6 is applied via a third frequency-divider circuit 7. The output of comparator circuit 5 is connected to the tuner circuit varicap diode voltage control input via amplifier and filtering circuit 8.

Number 10 indicates a control unit consisting of a keyboard which, besides the control keys not shown, such as the on/off switch and volume, brightness, contrast and color adjustment controls, also contains 10 number keys marked 0 to 9 (or letter keys marked A, B, C, D, E, F, G, H, I, L) and 7 auxiliary keys marked +, -, T, C, OR, M, CT (or +, -, R1, R2, R3, R4, CT).

This control unit is connected to a first group of eight input-output terminals of processing unit or circuit 11 and to the address inputs of memory circuit 12. The said processing unit also has a second set of eight input-output terminals connected to the data input-output terminals of memory circuit 12 and the inputs of character generator circuit 16. This, in turn, is connected to display device 9 (including the kinescope on the set) while a third group of 16 terminals is connected to:

12 programming inputs of 12-bit divider 4;

2 band-switch inputs (U and BIII) of tuner 2;

1 control input of character generator circuit 16;

a first input of combiner circuit 14.

Memory circuit 12 has further control terminals connected to the output of combiner circuit 14 which receives a signal from circuit 11 at a second input and a signal from on-detector circuit 15 at a third. Circuit 15 receives a signal from the power mains to which the television set is connected and also has its output connected to a RESET input of circuit 11.

Memory 12 and the low-current-absorption CMOS combiner circuit 14 are connected to a local battery supply source 13. The circuit operates as follows:

Circuits 3, 4, 5 and 8, together with the varicap-diode-controlled local oscillator (VCO) in tuner 2, form a phase lock loop controlled by the reference signal generated by quartz generator 6 and divided by divider 7 according to the known technique.

The function of divider circuit 3 is to reduce the frequencies involved to more easily processable levels while programmable divider 4 enables locking to be affected for a number of local oscillator frequencies, that is, it acts as a frequency synthesizer circuit.

In fact, after selecting division number N for divider circuit 4, phase-frequency comparator 5 supplies circuit 2, via amplifier 8, with voltage for obtaining the following condition: ##EQU1## in which f2 is the oscillation frequency of the local oscillator circuit in tuner 2, f6 is the oscillation frequency of reference oscillator circuit 6, N₂, N₁ and N are the division ratios of dividers 3, 6 and 4 respectively, while P=f6 N₁ /N₂ indicates the system pitch, that is, the amount by which local oscillator frequency varies alongside variations in number N.

The receiver must be capable of tuning into broadcasting stations of a given transmission standard, e.g. C.C.I.R./B-G, with channeling as agreed at the 1961 European Radio Broadcasting Conference in Stockholm, that is, broadcasting stations with one-step spacing between adjacent 7 MHz channels on the I and III (VHF) bands and 8 MHz channels on the IV and V (UHF) bands with a 5 MHz video signal band width. These broadcasting stations fall within television channels 2 and 69 (video carrier frequencies 48.25 and 855.25 MHz respectively) with 38.9 MHz intermediate frequency IF. This means the local oscillator on the tuner must be capable of generating frequencies ranging from 87.15 to 894.15 MHz. A 0.25 MHz pitch was selected which, according to equation 2 gives the following values for the two above mentioned channels: ##EQU2## By varying number N between these maximum and minimum values, any television channel on the VHF and UHF bands can be tuned into with a maximum error of 125 KHz.

Not all of this frequency range can be utilized so the tuner is provided with two band switch inputs U (UHF/VHF) and B (BIII/BI) to ensure only effective bands are covered. Divider 3 is a high-speed ECL type which divides by 64 (SP 8750). Divider 4 is a programmable TTL which can operate up to frequencies of about 15 MHz (3×SN74LS191). Circuits 5, 6 and 7 consist of an SP8760 integrated circuit with 250 KHz frequency quartz and N₂ =64 division ratio so that comparator circuit 5 operates at 3906.25 Hz frequency which corresponds to a quarter of line frequency. The function of amplifier and filter 8 is to adapt the output level of comparator 5 (max. 5 V) to the requirements of tuner 2 (max. 30 V) and provide the best possible filtering and lock speed conditions.

Circuit 11, which consists of a microprocessor unit, is designed to generate, among other things, N numbers and bandswitch signals for tuning into specific television broadcasting stations on the basis of data relative to the signals being tuned into supplied by the user from control keyboard 10. The said circuit 11 is also capable of supplying or receiving signals from memory 12 and sending signals to character generating circuit 16.

Number N is calculated using the following equation:

    N=(K.F+C)·4+S                                     (3)

The operations shown are performed by means of a series of elementary operations by an arithmetical-logic unit (ALU) on the basis of instructions contained in a (ROM) program memory contained in the processing circuit 11 and performed, in this case, using an F8 microprocessor. Constant correction C and factor F depend on the band selected; K is the channel number according to the said standard and the S variable can be changed for performing fine tuning corrections.

If channel number K is changed, we only get the frequencies corresponding to standard channels with a pitch equal to F (8 MHz for UHF and 7 for VHF), whereas one-unit variation of S causes frequency shifts of 0.25 MHz.

With appropriate control from the keyboard, various modes are possible for tuning into a given broadcasting station partly using known methods.

Whenever any one of the keys is pressed, processing unit 11 sends an ISO-coded 48-character sequence to character generator 16 which is displayed on the television screen in a three 16-character line arrangement.

This sequence always includes a time indication (hours, minutes, seconds). The remainder consists partly of fixed data from the ROM program memory (e.g. "CHANNEL" and "KEY" shown in FIG. 1) and partly of variable data depending on the controls activated by the user and the situation resulting from them which is memorized in a memory buffer inside unit 11 (e.g. the letter T indicating operation mode in the top right-hand corner of FIG. 1; figures 21-01, also in FIG. 1 following the "CHANNEL" indication which show the channel number and tuning correction).

The time indication is corrected automatically each second even if no key is pressed in the meantime.

When one of the "T", "C", "OR" or "M" keys is pressed, the corresponding operation mode is set and memorized in the memory buffer of processing unit 11. At the same time, one or more question marks are entered into the buffer at appropriate points to guide the user to the next control operation. The content of the buffer is then transmitted, of course, to the character generator and displayed on the television screen.

A few examples will now be given to give a clearer idea of this point.

When key "T" is pressed, the display shows:

00:MM:SS T

KEY ?

In this way, the user is informed that he has selected mode "T" (memory selection) and that the device expects a number key to be pressed (that is, an emitter memory key number). N.B.: 00:MM:SS in the above example stands for the time indication (hours, minutes, seconds).

When key "C" is pressed, the display shows:

00:MM:SS C

CHANNEL ??

In this way, the user is informed that he was selected mode "C" (direct selection) and that the device expects two number keys to be pressed (required channel number). If the number formulated by these two keys corresponds to a channel in the standard, the said number will be displayed in place of the two question marks beside the "CHANNEL" indication. If the channel number does not correspond to one in the standard, the display shows:

00:MM:SS C

CHANNEL ??

88

In this way, the user is informed that the control set (channel 88 not covered by the C.C.I.R. standard) has not been performed and that the device is awaiting further instructions. When key "OR" is pressed (causing the generation of a time reset control signal which is applied to processing unit 11), the display shows:

??:??:?? T

CHANNEL 21+01

KEY 0 OR

This tells the user that the television set is still set to mode "T", that it is tuned to channel 21 with a tuning correction equivalent to one frequency shift over 250 KHz, memorized on key 0, and that the device expects six number keys to be pressed one after the other corresponding to the hours, minutes and seconds the clock is to be reset to. As the six keys are pressed, the corresponding number is displayed in place of the "OR" indication and pairs of numbers replace the "??" corresponding to the hours, minutes and seconds, provided the numbers are acceptable.

In fact, the device checks the set numbers and, if the hour number is over 23 or the number corresponding to the tens of the minutes or seconds over 5, the two numbers (hours, minutes or seconds) are rejected and the two question marks are left displayed to inform the user that the device is waiting for another pair of acceptable numbers to be set. After the operation has been performed, the clock starts counting from the time set by the user.

The device is so designed that, following a power cut, a series of zeros is displayed for the hours, minutes and seconds and the clock remains in this condition to inform the user that the power supply has temporarily been cut off.

When the "M" key is pressed, the display shows:

00:MM:SS T

CHANNEL 21+01

KEY #? M

This tells the user that the television is still set to "T" mode, that it is tuned to channel 21 with +01 tuning and that the set is waiting for a number key to be pressed to memorize the channel tuned into. If key "0" is pressed, for example, the display shown in FIG. 1 appears and the channel is associated with key "0" for memory selection. If key "+" is pressed, the display shows:

00:MM:SS T

CHANNEL 21+02

KEY 0

This tells the user that the television is still set to "T" mode and that excess tuning corrections are being made, that is, towards the audio carrier of the received video signal. Circuit 11 supplies the programmable divider circuit, with a suitable modified number N and this tuning condition is automatically associated in the memory with key "0". Operation is similar when key "-" is pressed except for the direction of the tuning adjustment (towards the video). Once nominal tuning is obtained, the "+" sign and the following number are cancelled while, for more defective tuning conditions, the "-" sign appears followed by the number of displacements made. The system is so designed to limit maximum variations to the -16 to +15 range. Of course, the tuning correction can be made in the same way even with the set in the direct selection mode (mode "C").

In this case though, the operation does not involve automatic memorization. For the channel and obtained tuning condition to be memorized, the "M" key must be pressed, followed by a number key.

When the "CT" (keyboard switch) key is pressed, the display shows:

00:MM:SS *T*

CHANNEL 21+01

KEY 0

This tells the user ("*" beside the mode indication) that the device is set to perform a further series of functions corresponding to the second indication on each key. Following this operation, the processing circuit 11 supplies character generator 16 with a switch signal to switch the color of the writing on the screen or the background color so as to make it even more clear to the user that the controls available from that time on correspond to second key indications (this applies, of course, to color television sets).

If one of the keys marked "A" to "L" is pressed, the display shows:

00:MM:SS *C*

CHANNEL A

This tells the user that the television is set to mode "C" but, in this case, channels can be selected directly according to the Italian standard by pressing a single key with indication of the received channel.

When one of keys R1, R2, R3 or R4 is pressed, the display shows, for example:

00:MM:SS *1*

CHANNEL 21+01

KEY 0 RA

This tells the user that the set is performing an automatic scanning operation, for example type 1, or is scanning all the channels in the memory.

Scanning progresses automatically every two seconds with indications in each case of the key number and associated channel. At the same time, processing circuit 11 generates the relative N numbers for receiving the channel. Scanning stops when any other key is pressed. If the "+" or "-" key is pressed, the device remains set for manual advance or reversing (every time the "+" key is pressed, the key number is increased and decreased every time the "-" key is pressed). If the "CT" key is pressed, the device switches back to the first keyboard and awaits further instructions, in particular, tuning correction or memorization controls. Similarly, if key R2 is pressed after selecting the second keyboard using the "CT" key, this starts a type 2 scanning operation of all the standard channels (one switch per second). This can be stopped in the same way as type 1 scanning.

If key R3 is pressed, this starts a continuous scanning operation of the frequency band in 1 MHz steps, that is, 4 fine tuning switches per second, to detect any transmitters operating over non-standard frequencies. The same type of scanning operation, though at reduced speed (one switch every two seconds), is started pressing key R4.

The "KEY" indication is not displayed during type 2, 3 and 4 scanning operations.

Display or omission of the fixed "CHANNEL" and "KEY" indications depends on whether the indication or blank sectors of the ROM memory are utilized. Circuit 11 also comprises a timer which, 15 seconds after the last key has been activated, supplies a switch signal (bit 6 port 1) to character generator 16 which reduces the display to one line and also halves the height of the characters (7 instead of 14 television lines) to reduce disturbance to the picture. This switch signal, of course, is not supplied during automatic scanning or clock adjustment.

To prevent memorized data being lost during a power outage provision is made for a battery-supplied outside RAM memory 12. Whenever a memorization operation is performed, processing unit 11 updates the information in the RAM memory. When power supply returns to normal, the same unit 11 calls up the data memorized in the RAM memory.

"ON RESET" circuit 15 and combiner circuit 14 protect the data contained in RAM memory 12 during transient states between power supply failure and restoration.

Operation of processing unit 11 is shown more clearly in the elementary logic function block diagrams in FIGS. 2, 3 and 4.

FIG. 2 shows operation mode and relative indication selection;

FIG. 3 shows updating of the data in outside RAM memory 12;

FIG. 4 shows data being called up from the outside RAM memory following restoration of the power supply.

Number 20 in FIG. 2 indicates a timer which sets a switch circuit, 22, with its output usually towards block 23 and supplies an RTI signal to block 21 which reads the controls set on the keyboard. Block 21, via switch 22, supplies a signal to block 23 which ascertains the presence of a new order. The "NO" output supplies the RTI signal which reactivates reading block 21 while the "YES" output activates block 24 which ascertains whether the key pressed was a mode key. The "NO" output of block 24 activates block 25 which examines the operation mode selected and, in turn, activates block 26 which, depending on the mode chosen, combines and supplies the indication sequence to the character generator for display. Block 26 then activates block 27 which examines the number keys pressed and activates block 28 which ascertains whether the corresponding order is feasible.

The "NO" output of the block 28 (control not feasible, e.g. the number does not correspond to a standard number channel) activates a following block 34 which inserts question marks at appropriate points in the buffer to inform the user that the control is not feasible and transmits them to character generator 16 (FIG. 1). Block 34 then supplies an RTI signal to block 21 which reads the keyboard once more awaiting further instructions.

The "YES" output of block 28 activates block 29 which sends the channel or key numbers to the buffer, usually the numbers of the order received, transmits the numbers to the character generator and, finally, activates block 30 which calculates number N according to equation (3) and sends this number to programmable divider 4 (FIG. 1) to obtain the required tuning. Finally, block 30 supplies the RTI signal to block 21.

The "YES" output of block 24 activates block 36 which inserts the indications and question marks in the buffer and transmits them to the character generator (as described already). Block 36 then supplies block 21 with the RTI signal. After a set length of time (about 4 milliseconds), depending on circuit 20, switch 22 positions itself with its output towards count circuit 31 which, after a set number of pulses (about 250) per second, supplies a signal to block 32 which updates the clock numbers in the buffer and activates block 33 which sends the data contained in the buffer to the character generator and then supplies an RTI signal to block 21. Number 40 in FIG. 3 indicates a block for ascertaining whether the operation selected involves memorization. The "NO" output supplies a signal which activates block 25 (FIG. 2) while the "YES" output activates in turn:

block 41, which examines the number of the key pressed;

block 42, which memorizes the channel number and tuning in the registers corresponding to the said key;

block 43, which supplies an enabling signal (C.E.) and a first address for the outside memory circuit 12;

block 44, which supplies the channel number data and a memorizing pulse (WRITE) to the same circuit 12;

block 45, which supplies the new address;

block 46, which supplies the tuning data and memorizing pulse to memory 12.

Number 50 in FIG. 4 indicates a block which, following an "ON RESET" signal from circuit 15 in FIG. 1, supplies an output enabling (O.E.) signal to memory 12 as well as a signal for activating in turn:

block 51, which supplies the address to memory 12;

block 52, which reads the data from memory 12 and loads it into the registers in unit 11 of FIG. 1;

block 53, which calculates the new address;

block 54, which ascertains whether all the cells in memory 12 have been read. The "NO" output of block 54 supplies a signal for activating block 51 once more. The "YES" output activates block 55 which sets to mode "T" (memory selection) and key "0" and supplies an activation signal to block 25 of FIG. 2.

For further information concerning operation of the device, refer to Italian patent application No. 69950-A/77, noted above, which describes a device partly similar to the present one. In the actual device, a Fairchild F8 microprocessor unit was chosen for processing unit 11 which comprises a 3850 C.P.U., 3861 P.I.O., 3853 S.M.I. and two PROM F93448 memories. Each of the said two PROM memories comprises a connection matrix with a 512×8 format, input and address decoding circuits and output buffer circuits.

Each connection may be open or closed and represents permanent elementary data (bit) 1 or 0 respectively. Each group of 8 connections, addressed by one of the 512 address input combinations, represents an elementary 8-bit instruction or word (byte). By applying all the possible address combinations at the input, all the data contained in the ROM can be obtained at the output in word form.

These connections are described in the following tables for the circuit. The left-hand columns show the addresses, using hexadecimal notation, and the right-hand ones the connections of the corresponding memory cell. Number 1 refers to an open connection with logic 1 at the output while 0 refers to a closed connection.

As each memory cell consists of 8 connections, this means it can be represented with a combination of 8 binary figures. For the sake of simplicity, the hexadecimal system was used on the following tables, so that, for example, EA for base 16, which corresponds to 11101100 of base 2, indicates that the corresponding memory cell has connections 1, 2, 3, 5 and 6 open and the rest closed.

                  TABLE 1                                                          ______________________________________                                         ADDRESS   CODE         ADDRESS   CODE                                          ______________________________________                                         0000      70           000C      04                                            0001      B5           000D      6A                                            0002      B1           000E      7A                                            0003      B6           000F      5C                                            0004      BE           0010      6D                                            0005      BF           0011      5C                                            0006      B4           0012      7F                                            0007      65           0013      58                                            0008      6F           0014      18                                            0009      5E           0015      07                                            000A      8F           0016      67                                            000B      FE           0017      5C                                            0018      66           0031      70                                            0019      5E           0032      BD                                            001A      8F           0033      5B                                            001B      FE           0034      B5                                            001C      20           0035      90                                            001D      10           0036      12                                            001E      0B           0037      1B                                            001F      24           0038      A5                                            0020      90           0039      EB                                            0021      B5           003A      84                                            0022      A4           003B      FD                                            0023      5C           003C      59                                            0024      0A           003D      21                                            0025      1F           003E      10                                            0026      25           003F      49                                            0027      28           0040      94                                            0028      94           0041      19                                            0029      F5           0042      EB                                            002A      7C           0043      5B                                            002B      06           0044      91                                            002C      15           0045      F3                                            002D      5A           0046      73                                            002E      B1           0047      BE                                            002F      72           0048      1A                                            0030      BC           0049      67                                            004A      4B           0063      03                                            004B      21           0064      66                                            004C      1F           0065      6B                                            004D      59           0066      5C                                            004E      6F           0067      69                                            004F      25           0068      5C                                            0050      09           0069      29                                            0051      81           006A      02                                            0052      1A           006B      06                                            0053      25           006C      47                                            0054      0F           006D      56                                            0055      81           006E      49                                            0056      32           006F      57                                            0057      29           0070      5E                                            0058      02           0071      46                                            0059      03           0072      5D                                            005A      1A           0073      E8                                            005B      EB           0074      84                                            005C      5B           0075      1D                                            005D      21           0076      66                                            005E      10           0077      6A                                            005F      20           0078      00                                            0060      FA           0079      CC                                            0061      94           007A      91                                            0062      02           007B      17                                            007C      7F           0095      25                                            007D      5C           0096      0D                                            007E      6E           0097      84                                            007F      03           0098      0A                                            0080      5D           0099      81                                            0081      5C           009A      23                                            0082      67           009B      25                                            0083      5E           009C      0F                                            0084      8F           009D      84                                            0085      FE           009E      40                                            0086      90           009F      29                                            0087      E2           00A0      01                                            0088      25           00A1      3B                                            0089      0B           00A2      67                                            008A      81           00A3      6C                                            008B      51           00A4      03                                            008C      06           00A5      5C                                            008D      03           00A6      7D                                            008E      5E           00A7      66                                            008F      5D           00A8      6A                                            0090      7F           00A9      06                                            0091      5E           00AA      55                                            0092      02           00AB      20                                            0093      67           00AC      10                                            0094      6F           00AD      52                                            00AE      20           00C7      E4                                            00AF      D3           00C8      5C                                            00B0      5C           00C9      67                                            00B1      47           00CA      6C                                            00B2      E8           00CB      47                                            00B3      94           00CC      5C                                            00B4      03           00CD      E6                                            00B5      57           00CE      84                                            00B6      56           00CF      9A                                            00B7      46           00D0      47                                            00B8      15           00D1      13                                            00B9      C7           00D2      24                                            00BA      51           00D3      10                                            00BB      90           00D4      0B                                            00BC      1D           00D5      4D                                            00BD      55           00D6      51                                            00BE      03           00D7      4C                                            00BF      5E           00D8      52                                            00C0      8F           00D9      29                                            00C1      FE           00DA      01                                            00C2      66           00DB      84                                            00C3      5E           00DC      90                                            00C4      5C           00DD      4A                                            00C5      6A           00DE      66                                            00C6      20           00DF      4C                                            00E0      E8           00F9      13                                            00E1      84           00FA      B5                                            00E2      35           00FB      05                                            00E3      67           00FC      24                                            00E4      20           00FD      10                                            00E5      DD           00FE      0B                                            00E6      5C           00FF      72                                            00E7      6B           0100      59                                            00E8      4D           0101      41                                            00E9      CE           0102      5D                                            00EA      1F           0103      B4                                            00EB      84           0104      01                                            00EC      2B           0105      EA                                            00ED      20           0106      B5                                            00EE      F3           0107      EA                                            00EF      5D           0108      B5                                            00F0      47           0109      1F                                            00F1      5C           010A      B5                                            00F2      E8           010B      05                                            00F3      84           010C      42                                            00F4      31           010D      5C                                            00F5      A1           010E      39                                            00F6      EA           010F      94                                            00F7      B1           0110      F3                                            00F8      4C           0111      70                                                                   0112      B4                                            0113      B5           012C      52                                            0114      A1           012D      6B                                            0115      EA           012E      4E                                            0116      B1           012F      C8                                            0117      70           0130      81                                            0118      57           0131      55                                            0119      45           0132      6C                                            011A      06           0133      70                                            011B      03           0134      CC                                            011C      67           0135      81                                            011D      6F           0136      BC                                            011E      5E           0137      70                                            011F      5C           0138      57                                            0120      6C           0139      90                                            0121      4C           013A      4A                                            0122      E8           013B      49                                            0123      94           013C      23                                            0124      60           013D      0E                                            0125      90           013E      94                                            0126      5B           013F      1E                                            0127      13           0140      20                                            0128      18           0141      E2                                            0129      24           0142      5E                                            012A      16           0143      20                                            012B      C2           0144      DF                                            0145      5C           015E      E8                                            0146      6B           015F      84                                            0147      4C           0160      21                                            0148      C8           0161      46                                            0149      91           0162      25                                            014A      04           0163      05                                            014B      03           0164      91                                            014C      5D           0165      0C                                            014D      5C           0166      00                                            014E      65           0167      24                                            014F      68           0168      03                                            0150      4A           0169      04                                            0151      04           016A      24                                            0152      7F           016B      65                                            0153      5D           016C      0B                                            0154      5C           016D      46                                            0155      6B           016E      5D                                            0156      5D           016F      47                                            0157      5C           0170      5C                                            0158      6E           0171      7F                                            0159      5D           0172      57                                            015A      5D           0173      68                                            015B      90           0174      4D                                            015C      25           0175      15                                            015D      46           0176      CC                                            0177      25           0190      53                                            0178      23           0191      41                                            0179      91           0192      05                                            017A      D4           0193      25                                            017B      90           0194      01                                            017C      05           0195      81                                            017D      7F           0196      E7                                            017E      66           0197      25                                            017F      5E           0198      79                                            0180      5C           0199      91                                            0181      29           019A      E3                                            0182      02           019B      F8                                            0183      06           019C      25                                            0184      67           019D      09                                            0185      6B           019E      91                                            0186      03           019F      DE                                            0187      5E           01A0      70                                            0188      8F           01A1      CE                                            0189      FE           01A2      91                                            018A      66           01A3      04                                            018B      5E           01A4      03                                            018C      5D           01A5      5D                                            018D      67           01A6      5E                                            018E      70           01A7      66                                            018F      50           01A8      41                                            01A9      25           01C3      C9                                            01AA      69           01C4      51                                            01AB      81           01C5      25                                            01AC      0B           01C6      14                                            01AD      F8           01C7      91                                            01AE      2A           01C8      4A                                            01AF      03           01C9      13                                            01B0      E0                                                                   01B1      8E           01CA      C1                                            01B2      24           01CB      13                                            01B3      02           01CC      C1                                            01B4      51           01CD      59                                            01B5      16           01CE      01                                            01B6      53           01CF      25                                            01B7      41           01D0      69                                            01B8      14           01D1      81                                            01B9      5D           01D2      07                                            01BA      13           01D3      03                                            01BB      59           01D4      5D                                            01BC      13           01D5      79                                            01BD      13           01D6      8E                                            01BE      C9           01D7      16                                            01BF      59           01D8      5E                                            01C0      41           01D9      41                                            01C1      F8           01DA      25                                            01C2      5E           01DB      04                                            01DC      20           01EE      00                                            01DD      45           01EF      38                                            01DE      81           01F0      29                                            01DF      05           01F1      00                                            01E0      74           01F2      37                                            01E1      50           01F3      29                                            01E2      20           01F4      00                                            01E3      AF           01F5      48                                            01E4      C3           01F6      29                                            01E5      90           01F7      00                                            01E6      2A           01F8      A2                                            01E7      FF           01F9      29                                            01E8      FF           01FA      00                                            01E9      FF           01FB      C9                                            01EA      FF           01FC      29                                            01EB      FF           01FD      01                                            01EX      FF           01FE      84                                            01ED      29           01FF      FF                                            ______________________________________                                    

                  TABLE 2                                                          ______________________________________                                         ADDRESS    CODE        ADDRESS   CODE                                          ______________________________________                                         0200       29          02ED      5D                                            0201       02          02EE      25                                            0202       DD          02EF      05                                            0203       29          02F0      81                                            0204       03          02F1      1C                                            0205       26          02F2      70                                            0206       29          02F3      5E                                            0207       02          02F4      5C                                            0208       7A          02F5      6C                                            0209       FF          02F6      39                                            020A       FF          02F7      94                                            020B       FF          02F8      EF                                            020C       FF          02F9      69                                            020D       FF          02FA      20                                            020E       FF          02FB      67                                            020F       FF          02FC      DC                                            0210       90          02FD      5E                                            0211       11          02FE      14                                            0212       20          02FF      CC                                            0213       20          0300      5D                                            0214       C1          0301      25                                            0215       51          0302      01                                            0216       13          0303      81                                            0217       13          0304      09                                            0218       13          0305      4C                                            0219       59          0306      25                                            021A       41          0307      03                                            021B       14          0308      81                                            021C       12          0309      04                                            021D       24          030A      70                                            021E       08          030B      5E                                            021F       50          030C      5D                                            0220       20          030D      4C                                            0221       52          030E      F8                                            0222       C9          030F      5C                                            0223       51          0310      6F                                            0224       40          0311      4C                                            0225       19          0312      21                                            0226       13          0313      01                                            0227       13          0314      CB                                            0228       50          0315      21                                            0229       70          0316      1F                                            022A       C2          0317      25                                            022B       81          0318      1C                                            022C       04          0319      20                                            022D       70          031A      F3                                            022E       90          031B      91                                            022F       07          031C      05                                            0230       25          031D      28                                            0231       20          031E      02                                            0232       81          031F      9C                                            0233       03          0320      03                                            0234       20          0321      05                                            0235       20          0322      71                                            0236       52          0323      04                                            0237       41          0324      1B                                            0238       14          0325      0C                                            0239       12          0326      4B                                            023A       12          0327      F8                                            023B       C0          0328      06                                            023C       50          0329      25                                            023D       41          032A      09                                            023E       13          032B      81                                            023F       13          032C      62                                            0240       C2          032D      03                                            0241       59          032E      6C                                            0242       40          032F      5C                                            0243       19          0330      6F                                            0244       18          0331      5E                                            0245       B1          0332      20                                            0246       01          0333      E2                                            0247       25          0334      5D                                            0248       70          0335      02                                            0249       84          0336      13                                            024A       08          0337      18                                            024B       25          0338      24                                            024C       74          0339      16                                            024D       84          033A      25                                            024E       04          033B      FE                                            024F       70          033C      91                                            0250       90          033D      08                                            0251       02          033E      02                                            0252       72          033F      55                                            0253       C9          0340      20                                            0254       18          0341      D1                                            0255       B0          0342      5C                                            0256       01          0343      71                                            0257       51          0344      04                                            0258       67          0345      50                                            0259       68          0346      66                                            025A       03          0347      6A                                            025B       C2          0348      45                                            025C       84          0349      24                                            025D       1D          034A      F5                                            025E       50          034B      5C                                            025F       20          034C      25                                            0260       FB          034D      02                                            0261       5C          034E      84                                            0262       81          034F      11                                            0263       08          0350      91                                            0264       20          0351      28                                            0265       FD          0352      47                                            0266       5C          0353      C0                                            0267       40          0354      81                                            0268       18          0355      02                                            0269       1F          0356      79                                            026A       50          0357      25                                            026B       20          0358      09                                            026C       67          0359      81                                            026D       59          035A      02                                            026E       70          035B      70                                            026F       D9          035C      57                                            0270       30          035D      29                                            0271       94          035E      01                                            0272       FD          035F      F9                                            0273       69          0360      20                                            0274       59          0361      10                                            0275       14          0362      52                                            0276       5D          0363      70                                            0277       49          0364      C0                                            0278       F8          0365      91                                            0279       5C          0366      03                                            027A       7F          0367      24                                            027B       53          0368      66                                            027C       A1          0369      D1                                            027D       22          036A      25                                            027E       40          036B      01                                            027F       B1          036C      92                                            0280       28          036D      03                                            0281       02          036E      20                                            0282       9C          036F      79                                            0283       00          0370      25                                            0284       25          0371      79                                            0285       C9          0372      81                                            0286       91          0373      02                                            0287       12          0374      72                                            0288       84          0375      51                                            0289       04          0376      29                                            028A       29          0377      01                                            028B       01          0378      FC                                            028C       ED          0379      40                                            028D       45          037A      13                                            028E       06          037B      13                                            028F       70          037C      C2                                            0290       57          037D      81                                            0291       20          037E      05                                            2092       FD          037F      20                                            0293       54          0380      1C                                            2094       03          0381      90                                            0295       67          0382      E0                                            0296       6F          0383      25                                            0297       5E          0384      1C                                            0298       5C          0385      81                                            0299       29          0386      04                                            029A       01          0387      70                                            029B       F0          0388      90                                            029C       2A          0389      D9                                            029D       03          038A      52                                            029E       D0          038B      41                                            029F       20          038C      90                                            02A0       80          038D      DD                                            02A1       B4          038E      57                                            02A2       65          038F      77                                            02A3       68          0390      56                                            02A4       74          0391      5C                                            02A5       59          0392      29                                            02A6       7C          0393      01                                            02A7       50          0394      F6                                            02A8       16          03B0      DF                                            02A9       B4          03B1      CE                                            02AA       CA          03B2      EF                                            02AB       B4          03B3      DF                                            02AC       39          03B4      DF                                            02AD       94          03B5      CA                                            02AE       FA          03B6      ED                                            02AF       0A          03B7      DF                                            02B0       25          03B8      FC                                            02B1       34          03B9      FE                                            02B2       94          03BA      F1                                            02B3       0A          03BB      FE                                            02B4       67          03BC      F3                                            02B5       70          03BD      FA                                            02B6       CC          03BE      DF                                            02B7       81          03BF      DF                                            02B8       03          03C0      C7                                            02B9       7A          03C1      FE                                            02BA       8E          03C2      DF                                            02BB       66          03C3      EB                                            02BC       6E          03C4      FE                                            02BD       4C          03C5      EC                                            02BE       24          03C6      EB                                            02BF       30          03C7      F0                                            02C0       18          03C8      DF                                            02C1       B4          03C9      DF                                            02C2       CA          03CA      C7                                            02C3       B4          03CB      FE                                            02C4       0A          03CC      DF                                            02C5       1F          03CD      DF                                            02C6       0B          03CE      DF                                            02C7       30          03CF      DF                                            02C8       94          03D0      DF                                            02C9       F4          03D1      DF                                            02CA       CA          03D2      DF                                            02CB       84          03D3      DF                                            02CC       07          03D4      FF                                            02CD       7B          03D5      FF                                            02CE       59          03D6      FF                                            02CF       75          03D7      FF                                            02D0       50          03D8      FF                                            02D1       90          03D9      FF                                            02D2       D6          03DA      FF                                            02D3       B4          03DB      FF                                            02D4       33          03DC      FF                                            02D5       81          03DD      FF                                            02D6       06          03DE      FF                                            02D7       53          03DF      FF                                            02D8       A1          03E0      05                                            02D9       21          03E1      07                                            02DA       BF          03E2      14                                            02DB       B1          03E3      00                                            02DC       1C          03E4      01                                            02DD       34          03E5      03                                            02DE       94          03E6      05                                            02DF       41          03E7      07                                            02E0       72          03E8      07                                            02E1       59          03E9      07                                            02E2       20          03EA      D1                                            02E3       FE          03EB      D2                                            02E4       54          03EC      D3                                            02E5       65          03ED      D4                                            02E6       6F          03EE      D5                                            02E7       20          03EF      D6                                            02E8       67          03F0      D7                                            02E9       DC          03F1      D8                                            02EA       5E          03F2      D9                                            02EB       14          03F3      DC                                            02EC       CC                                                                  ______________________________________                                    

The above tables contain, in coded form, one possible sequence of elementary operations for performing, via the microprocessor system indicated, the functions shown in the block diagrams and foregoing description.

FIG. 5 shows a more detailed representation of the block diagram of character generator 16 in FIG. 1.

Number 60 in FIG. 5 indicates a character count circuit for supplying the addresses to character memory 61. This has a 48×6 format for containing the 48 characters transmitted periodically by processing unit 11.

The six INPUT/OUTPUT terminals of the said memory are connected to six output terminals of PORT 71 of processing unit 11. These are also connected to six inputs of character ROM 62.

This may be a Fairchild 3258 type, for memorizing 64 characters for each of which it supplies an image consisting of a 5×7 point matrix. Each character is separated vertically from the next by two lines of blanks.

A built-in counter, which receives a clock signal with horizontal scanning frequency FH from the television circuits and a reset signal R1 from circuit 60, scans the following point lines of the said matrix.

The five outputs of the said ROM 62 are connected to a parallel-series converter circuit 63 which transforms the 5 signals received from the 5 outputs into a series signal. It also adds a suitable number of blanks (e.g. 3) on to the end of the 5 signals to separate the characters horizontally.

Circuit 63 receives a clock signal from oscillator circuit 66 the frequency of which determines the width of each of the characters displayed on the screen. It also receives a LOAD signal "L" for each character (every 5+3=8 clock cycles in the example shown) from divider circuit 67 which, in turn, receives the clock signal from oscillator circuit 66. The signal thus received at the output of converter 63 is sent to combiner circuit 64 consisting of known logic elements (e.g. three 2-input AND gates each with a first input connected to the output of circuit 63 and a second connected to one of the outputs of circuit 65) which sends the said signal to one or more of its three outputs, marked R, G and B in the Figure, in response to the same number of control signals supplied by control circuit 65. The said outputs R, G and B are connected, in the known way, to the amplifier circuits of the color signals on the set so that the signals supplied by circuit 64 are added to the video ones of the received television signal.

Depending on the instructions received from circuit 65, it is possible to obtain the indications in any one of the three primary color combinations.

In FIG. 5, the control circuit 65 receives a control signal from an output of circuit 71 (port 4 of unit 11 in FIG. 1) so that the indications are displayed in green when the system is set to the first keyboard and yellow when it is set to the second.

Numbers 68, 69 and 70 indicate three switch circuits, similar to one another, controlled in parallel by a memory control signal DT supplied by a bit of port 1 of processing unit 11 in FIG. 1. Depending on the DT signal, these three switch circuits enable the FIG. 5 circuits to be set so as to load the data in memory 61 when the DT signal is present (high) and, vice versa, to set the same circuits for transmitting the data from the said memory to outputs R, G and B when the DT signal is absent (low) or when unit 11 is not transmitting characters to memory 61 (for display updating). To do this, when the DT signal is present, switches 68, 69 and 70 are positioned as shown by letter A in FIG. 5. This causes a reset pulse to be applied to terminals R2 and R3 of count circuit 60 and memory 61 is set to INPUT by the same DT signal applied to the input-output I/O control terminal.

Via switch circuit 68, count circuit 60 receives clock pulses DC from an output terminal of processing unit 11 of FIG. 1 (port 4). The same DC signal is also sent to the write control input "W" of memory 61.

In this way, for each clock pulse it receives, counter 60 supplies RAM memory 61 with addresses from 0 to 47. At the same time, unit 11 supplies the 48 signals (at port 4) received at the data input of the same memory so that they are memorized in the corresponding cells as a result of the "W" pulses.

When the DT signal is absent, on the other hand, (switches in position B), character counter 60 receives clock signals from circuit 66 via divider 67, reset signals with vertical scanning frequency fr at terminal R2, reset signals with horizontal scanning frequency FH at terminal R3 and a format-change signal "F" (controlled by a timer in processing unit 11, from processing unit 11. In this way, it supplies memory 61 with suitable addresses for arranging the 48 display characters in three 16-character lines, should signal "F" be present, or else it supplies the memory with only the first sixteen addresses for displaying a single 16-character line when signal "F" is absent. Alteernatively, character counter 60 can cut the size of the three sixteen character lines in half when the signal "F" is absent. Counter 60 also supplies combiner circuit 64 with a disabling circuit for disactivating it during the remaining television picture time. In this way, only a certain part of the screen is displayed, e.g. the top left-hand corner. If needed, the same disabling signal can be used for supplying a blank signal at an appropriate point in the television video amplification chain so as to blacken the background of the display to make the characters more visible.

A further output of circuit 71 (port 4 of unit 11) controls a switch, 72, between a BIP signal (which can be picked up at an appropriate point on the circuit, e.g. at the output of divider 7 of FIG. 1) and a first input of an adding circuit, 73, whose second input receives the audio B.F. signal of the received television signal picked up downstream from the manual volume adjuster. The output of the adding circuit is connected to the input of the B.F. amplifier, 74, on the set which pilots the loudspeaker 75.

In this way, under given circumstances, the processing unit 11 can control the sounding of an alarm for warning the user. The said circumstances may be:

(1) When the "M" memory key is pressed. The alarm reminds the user that the key has been pressed so as to prevent him from altering the content of the memory by mistake;

(2) when an unperformable instruction is given (e.g. the number of a non-existent channel or time) etc.

(3) when the maximum allowable limits have been reached for certain adjustments such as fine tuning corrections.

FIG. 6 gives a more detailed view of parts of circuits 12, 13, 14 and 15 in FIG. 1 showing memorization of the channels in the outside memory and maintenance of data during temporary power cuts. The said circuits 12, 13, 14 and 15 roughly correspond to the blocks marked 113, 100, 105 and 80 in FIG. 6.

Block 80 comprises a Zener diode, 83, connected between a +12 output of a supply circuit ("AC" voltage input, transformer 81 and rectifier 82) and a grounded resistor 84. The signal present at the resistor terminals is sent to an integrator circuit consisting of resistor 86, diode 87 and condenser 85.

The signal made available here, and inverted by inverter 88, is sent to inverter circuit 95 via integrator assembly consisting of resistor 93 and condenser 94, and also to the base of common-emitter transistor 90 via coupling resistor 89. The collector of transistor 90 is connected to a +5 supply voltage through resistor 92 and grounded through push-button switch 91 and supplies a reset signal to processing unit 11 (FIG. 1).

The +12 voltage is also supplied to the input of a stabilizer circuit 96 at the output of which, filtered by condenser 97, is made available the +5 supply voltage for supplying other circuits not shown in the Figure. The output of inverter 95 is connected to a first input of NAND gates 107 and 109 and to both inputs of NAND gate 106 which acts as an inverter. The output of the said gate 106 is connected to a reset input R4 of separator circuit 112 which receives the output signal of gate 107 at its disabling input C.D. via inverter circuit 110. Gate 107 receives a conditioning signal C.S. from processing unit 11 of FIG. 1 at its second input. The output of gate 107 is also connected to a disactivating input C.D. of memory 113.

A READ signal from processing unit 11 of FIG. 1 is sent via NAND gate 108, which acts as an inverter, to the read disabling "NR" input of memory 113. This input is also connected to a second input of gate 109 the output of which is connected to a write disabling "NW" input of the same memory 113.

The +5 voltage is also supplied to the anode of diode 101 at the cathode of which is connected a condenser, 104, the second terminal of which is grounded. Resistor 102 and 3 Volt battery 103, connected in series, are also connected parallel to condenser 104. The voltage available at the terminals of condenser 104 supplies memory 113, separator 112 and the 4 gates 106, 107, 108 and 109 contained in a single semiconductor body (CHIP).

Separator 112 has 5 inputs connected to 5 outputs of control circuit 111 (keyboard or remote-control receiver) and 5 outputs connected to 5 terminals of circuit 114 (port 5 of processing unit 11 in FIG. 1).

The same 5 outputs are also connected to 5 address inputs of memory 113.

The circuit described above operates as follows:

The function of block 100 is to generate a permanent supply voltage to keep memory 113 activated. In the event of a power cut, battery 103 supplies sufficient current to maintain the data in the memory through resistor 102. Vice versa, when power is being supplied from the mains, the +5 voltage is supplied to the memory via diode 101 and, at the same time, the battery is recharged slightly through resistor 102.

By means of Zener diode 83 and the integrator circuit comprising elements 85, 86 and 87, block 80 supplies a signal, at the output of inverter 95, after the +5 voltage, when the power supply is restored, and in advance of the said voltage when the power supply is cut off. In this way, the signals supplied by processing unit 11 to memory 113 cannot reach the memory during a power cut or during transient states.

Under the above conditions, gates 107, 108 and 109 are conditioned so as to protect memory 113 whereas gates 106 and 110 force separator 112 to supply a series of zeros at the output to prevent the memory from receiving chaotic address signals.

Block 80 also supplies, at the output of transistor 90, a signal similar to the one supplied by inverter 95 to keep processing unit 11 inactive during transient states and thus prevent uncontrolled operation. Push-button 91, however, enables a reset signal to be supplied manually to the said unit to commence the operation sequence from a preset point.

FIG. 7 shows a possible variation of one part of the circuit shown in FIG. 1. FIG. 7 only illustrates the parts which differ from FIG. 1 or which are connected differently.

Number 120 in FIG. 7 indicates a control keyboard which, besides the keys shown in FIG. 1 and not repeated here, comprises 6 keys marked "V+", "V-", "L+", "L-", C+" and "C-". The outputs of the said keyboard are connected to a group of input-output terminals 5 of processing unit 121 which is essentially the same as unit 11 in FIG. 1 from which it differs, among other things, by the provision of a further group of output terminals (ports) 6.

Six terminals of the said group are connected to six inputs of a digital/analogue converter 123 of the known type (e.g. consisting of a known network of R/2R resistors). The analogue output of the said converter is supplied to a switch circuit 124 with three outputs marked V, L and C in the Figure which are connected to three storage condensers 125, 126 and 127 respectively. Switch 124 also has two control input terminals connected to the remaining two output terminals of port 6 of unit 121 which receive the respective control signals for forwarding the analogue signal to one or other of condensers 125, 126 or 127.

The group of terminals or port 4 is connected to 8 input/output terminals of a RAM memory circuit 122. This replaces memory 12 of FIG. 1 from which it differs by the number of 8-bit cells (10×5 instead of 10×2). This memory also receives six address bits (instead of 5) from six output terminals (port 5) of unit 121.

The FIG. 7 circuit operates as follows:

When one of the six keys mentioned above is pressed (e.g. key "V+"), unit 121 supplies the character generating circuit with a combination of symbols which may be:

VVVVVVVV . . . . .

LLLLLL . . . . . . .

CCCCCCCCCCC . .

The line of symbols corresponding to the pressed key (V, L, C) is displayed with a different color from the rest. The number of characters per line is proportional to the corresponding analogue signal level (V, L, C) at that time. Whenever one of the + keys is pressed, the corresponding analogue level is increased 1/64 of maximum value. When an operation involving memorization is performed (e.g. whenever "KEY" operation mode is adjusted or the "M" key pressed), processing unit 121 transmits the relative data in digital form to memory 122 and has it memorized with much the same procedure already described and shown in FIG. 3. This means the data memory 122 is called upon to memorize for each of the 10 "KEYS" is of 5 types: channel, tuning, volume, brightness and color. For the sake of uniformity; the memory accepts 8-bit data whereas, the analogue adjustments, 6 bits, (64 levels) are more than enough so two bits are ignored.

Other ways exist of displaying analogue levels on the television screen using the character generator and circuit arrangement described in the present invention. Besides the one described above, the display could show any one of the following:

V*******<

L*****

C**********

or:

VOLUME 40?

BRIGHTNESS 30

COLOR 50

or:

V+++++

C-

In the first, the number of asterisks is proportional to the relative analogue signal level and the adjustment being made indicated by the symbol ">". In the second, the level is indicated by the number to the side of the adjustment item while the adjustment being made is indicated by the question mark. In the third, the number of "+" (or "-") signs is proportional to the increase (or decrease) made to the preset nominal level. Of course, the preselected, memorized levels are preserved in memory 122, even in the event of a power outage, thanks to the precautions already described which also apply to the embodiment of FIG. 7.

It may prove useful to apply the sound alarm described in FIG. 5 for analogue adjustments too, for example, when the maximum level is reached.

The advantages of the present invention will be clear from the foregoing description. However, a number of variations can be made. For example, in the description, it was supposed a particular type of 8-bit microprocessor system was used with a separate CPU and ROM. It is possible, and even convenient, to use other types of microprocessors with a higher number of internal RAM registers (e.g. 128) or a so-called monochip containing an internal RAM and timer circuit, besides the ROM, or a 16-bit microprocessor.

It may even prove useful to fit the receiver with a remote-control. In this case, a keyboard similar to the one described is combined on the portable transmitter part of the remote-control system. A further variation, to avoid duplicating the control keyboard, could be to provide accommodation in the receiver housing with electric contacts in which to connect the transmitter part for operating the local control.

Many other variations can be made without, however, departing from the scope of the present invention.

For example, besides the key arrangement in FIG. 1 for controlling channel selection or FIG. 7 for controlling analogue levels (V, L, C), a number of different combinations can be used even using other control components different from keys or push-buttons. 

I claim:
 1. Apparatus for use with a television receiver, said apparatus comprising:a power circuit for converting a mains power supply voltage to a reduced voltage which is applied as a power signal to several components of said television receiver, said power circuit generating said reduced voltage shortly after said mains power supply voltage is applied thereto and maintaining said reduced voltage until shortly after said mains power supply voltage is removed therefrom; a read/write memory for storing information relating to the operating parameters of said television receiver, said memory having data terminals, address terminals, and one or more control terminals for controlling operation of said memory; a control circuit for controlling said operating parameters of said television receiver as a function of said information stored in said memory and as a function of data signals applied thereto, said control circuit changing the values of said information stored in said memory by applying control signals to said data and address terminals of said memory in response to specific data signal applied to said control circuit; first means for generating a disable signal responsive to an interruption of said mains power supply voltage, said disable signal being generated before said reduced voltage is cut off in response to the removal of said mains power supply voltage from said power circuit, said disable signal continuing until after said reduced voltage is again generated by said power circuit in response to the reapplication of said mains power supply voltage to said power circuit; second means responsive to said disable signal for supplying a series of fixed signals to at least one of said data and address terminals of said memory; and third means responsive to said disable signal for applying to at least one of said control terminals of said memory an appropriate signal for preventing said information stored in said memory from being changed during the period in which said disable signal is generated.
 2. Apparatus according to claim 1, wherein said series of fixed signals is supplied to said address input terminals of said memory.
 3. Apparatus according to claim 1, wherein said series of fixed signals is a series of zeroes.
 4. Apparatus according to claim 1, wherein said control circuit for controlling said operating parameters of said television receiver comprises a processing unit, and wherein fourth means are provided for keeping said processing unit inactive during the period in which said disable signal is generated.
 5. Apparatus according to claim 1, further including an emergency power supply comprising:a battery; a resistor coupling said battery to said memory; and a diode for normally coupling said reduced voltage to said memory, the location of said diode being such that said reduced voltage normally charges said battery and such that said battery applies power to said memory when said reduced voltage is cut off. 